Guys, I need your serious opinions. One of my former experienced coworker is filing a new patent on service/technology. He wants me to be on his team for engineering architecture to develop the product. If it fails, we get nothing. If it successful then its big multimillion business. There will be around 5 people including him, 2 for engineering and architecture including me, and others for marking, strategic development etc. And he will be as a lead on all the teams. Now, I need to decide on how much to ask for share. Of course he wants at least 30%-40% more then we get for sure. Any suggestion? Is there any industry standard for such practices?